Set for blood processing

ABSTRACT

A tubular medical set as main blood flow tubing, a connected, flexible branch tube, a flow restriction device to suppress pressure pulses. The device is positioned to control flow through the branch tube. The flow restriction device permits substantially free, unhindered flow from the branch tube to the main blood flow tubing, while significantly restricting, but not completely blocking, flow from the main blood flow tubing to the branch tube.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation in part of application Ser. No. 09/432,555, filedNov. 3, 1999, now U.S. Pat. No. 6,517,508.

BACKGROUND OF THE INVENTION

The field of blood processing primarily comprises hemodialysis andplasmapheresis, although other forms of blood treatment may also beused, for example, hemoperfusion, passing blood through adsorbentcartridges, and the like. To accomplish this, blood sets are used toconvey blood from the patient to a blood processing device, and then toreturn the blood from the device back to the patient. The former bloodset is called the arterial set, while the latter set is called thevenous set.

In combination, the arterial and venous sets comprise several yards oftubing, and thus are rather cumbersome to handle. Furthermore, cost isof course a critical matter, especially when a patient has a chronicneed for treatment as in hemodialysis, so that even small cost savingscan add up to a substantial amount over a year or more of repeated usageof disposable arterial and venous sets.

Furthermore, priming of the sets is an issue requiring the skilledattention of technicians, so that any improvement or simplification inthe priming process, and other processes of use of the arterial andvenous sets, can be valuable.

By this invention, numerous improvements to conventional arterial andvenous blood sets are provided for reduction of cost and improved easeand efficiency of use.

DESCRIPTION OF THE INVENTION

By this invention, a combined arterial and venous blood tubing set maybe provided for the transport of blood between a patient and a bloodprocessing unit. The combined set comprises an arterial set componentwhich comprises arterial tubing having an arterial patient connector atone end and an arterial unit connector at the other end. A venous setcomponent of the set comprises venous tubing having a venous patientconnector at one end and a venous unit connector at the other end.

In accordance with this invention, the arterial and venous patientconnectors, and the arterial and venous unit connectors, arerespectively substantially and releasably directly connected to eachother in such manner that the arterial and venous set componentscooperate to form a loop.

This facilitates the installation of the sets into a hemodialysismachine, for example, resulting in greater ease of installation with asaving of time. Eventually, the set components wind up serving in thenormal manner of arterial and venous sets. Even with a relatively smallincrease or improvement in ease and time saving, the improvement can bequite substantial particularly in the treatment of chronic conditions,as in most hemodialysis, so that the effect of the improvement in timesavings can add up to a substantial amount over the course of a year.

Particularly, the arterial and venous unit connectors may be directlyconnected together with a frangible seal, to permit their breaking apartafter the combined set has been primed, for subsequent connection to ablood processing unit.

Thus, the fully primed arterial and venous sets may be directlyconnected to a reused dialyzer. Solution may then be circulated throughthe system with air being removed from the dialyzer, but no air beingsent to the dialyzer through the primed sets, which reduces the numberof air bubbles being trapped within the dialyzer itself. Air coming fromthe dialyzer will then be typically removed by a bubble trap in thesets, so that it is not recirculated again to the dialyzer.

By this invention, particularly wet, reused dialyzers (or other bloodprocessing devices) can be effectively primed to exhibit improvedperformance because of a reduced number of trapped air bubbles withinthe membrane system of the dialyzer.

The arterial and venous patient connectors of the respective arterialand venous sets may optionally be substantially directly connectedtogether by an interconnector tube to permit circulatory priming of thearterial and venous sets, and also to avoid the need of other endclosures at the arterial and venous patient connectors, if the arterialand venous sets are supplied to the user in interconnected form as inthis invention.

The interconnector tube preferably comprises a tube having a connectorsuch as a female luer connector at each end, for connection with thepatient connectors of the arterial and venous sets. Also, the tube mayhave an attached, integral cap to close an end of the tube afterdisconnection of one of the patient connectors. Thus, one of the patientconnectors may have its sterility preserved while the other patientconnector is being attached to a fistula set and access to the patient'sbloodstream is being obtained.

Priming of the connected arterial and venous sets can be performed in amanner similar to that disclosed in Utterberg U.S. Pat. No. 5,951,870,preferably with the modifications described below:

The arterial and venous sets respectively preferably have thesubstantially directly connected end connectors to form a closed loop asdescribed above. One may pass priming solution into and through aportion of the directly connected arterial and venous sets in a firstdirection that is reversed to the normal direction of blood flow throughthe sets, while removing air from one of the sets through a branchingport from one of the sets.

One also may pass priming solution into a second direction of flowopposite to the first flow direction through the system (which oppositedirection is the normal direction of flow through the system) whilecontinuing to remove air from the system through the port, untilsubstantially all air desired is removed from the arterial and venoussets.

Thereafter, with the flow stopped temporarily the unit arterial andvenous connectors are separated and connected to the blood processingunit such as a dialyzer preferably with the blood outlet at the top tofacilitate bubble removal. One then pumps the priming solution throughthe arterial and venous sets and the blood processing unit in the secondflow direction (i.e., the normal flow direction which is reversed to thefirst flow direction), to flush the sets and blood processing unit,without passing substantial amounts of air into the blood processingunit.

This method can be accomplished while pumping the solution with a flowpump such as a roller pump through the set, which operates in only asingle, pumped flow direction throughout the entire priming process, thenormal, second flow direction described above. The first flow direction,which is reverse to the second flow direction, may take place by gravityflow if desired. Preferably, the arterial and venous patient connectorsare substantially directly connected together throughout substantiallyall of the performance of the above method.

The invention also pertains to a tubular medical fluid set having anin-line bubble trap chamber having a top wall. The top wall defines aport which communicates with flow tubing of the tubular set. The portcommunicates with a port tube which extends into the chamber and has atube end which is spaced below the top wall, and preferably below theintended blood/air interface. The tube end defines a wall that directsflow out of the tube circumferentially into and through the bubble trapchamber. Thus, blood entering the chamber through the tube is directedcircumferentially about the chamber wall, the effect of which is todirect bubbles radially inwardly, rather than downward.

The chamber also preferably defines a baffle to convert circumferentialflow into turbulent flow at positions above the tube end wall and thecircumferentially directed blood and at the blood-air interface. Thisprevents formation of a blood whirlpool having a significant, centrallydepressed upper surface. Thus, the centrally disposed bubbles will riseto the top of the chamber to join an air space that is typically presentthere, without being sucked downwardly as would be caused by thepresence of such a blood whirlpool having a centrally depressed uppersurface.

Accordingly, the flow pattern of blood near the top of the bubble trapchamber described comprises a top segment of largely turbulent bloodflow, and a lower segment of largely circumferential blood flow.

As another aspect of this invention, priming of a tubular medical fluidset may take place, the set having an in-line bubble trap chamber,preferably on the venous set. One passes priming solution into thetubular set preferably at a point pre-pump on the arterial set andbubble trap chamber, while withdrawing air from the set through a portin an upper portion of the chamber. The port communicates with a porttube extending into the chamber in positions which are spaced below atop chamber wall.

Further in accordance with this invention, preferably the in-line bubbletrap chamber has an upper portion which defines a port that communicateswith the exterior. The port communicates with a port tube extending intothe chamber, having a port tube opening spaced below the top wall withinthe chamber, to automatically define a predetermined air volume andliquid level in the chamber approximately at or above the tube openingas the tubular set is filled with priming solution.

The bubble trap chamber top wall also may define an axially depressedportion which, in turn, defines a needle pierceable, resealableinjection site to permit an injection needle of at least about ½ inchneedle length to penetrate said injection site and to communicate withliquid below said liquid level which preferably is set by the port tubearrangement mentioned above.

Contrary to the prior art, this injection site carried on the top wallof a bubble trap chamber resides at a lower position from other portionsof the top wall, providing a desired inner volume under the otherportions for air above a liquid level. In combination with this, theresealable injection site is carried on the axially depressed portion ofthe top wall, so that the injection site is closer to the liquid levelwithin the bubble trap chamber, preferably permitting an injectionneedle of at least about ½ inch needle length to penetrate the injectionsite and to communicate with the liquid below the liquid level, whilestill permitting an air volume within the bubble trap chamber ofpreferably at least about 4 cc. This permits direct access to the bloodby a conventional hypodermic needle from the top of the chamber, forblood sampling from the chamber injection site, permitting infusion ofthe very expensive drug erythropoietin (“EPO”), with pump flushing ofthe needle several times, drawing blood into the needle and out again torinse all possible EPO into the set and then the patient, to avoidwasting of the highly valuable material.

Further in accordance with this invention, a tubular blood set fortransfer of blood between a patient and a blood treatment device hasmain blood flow tubing and a flexible branch tube connected in branchingrelation to the main tubing. The branch tube is adapted for connectionat its other end to a source of physiological, cell-free solution, as isconventional.

As particularly shown in Utterberg et al pending patent application Ser.No. 09/203,274, filed Dec. 1, 1998, some of the blood passing throughthe main blood flow tubing may extend into the branch tube to form ablood-solution interface, so that a pressure monitor which is alsoconnected to the branch tube is protected from contact with blood by thepresence of an amount of cell-free solution in the branch tube and anon-compressible, air-free pressure sensing path is provided through thecell free solution and the blood across the interface.

In accordance with this invention, to suppress pressure pulses from themain blood line tending to disrupt the blood-solution interface, aportion of the flexible branch tube is equipped with pulse suppressionmeans. Such means may comprise a partially collapsible portion of thebranch tube, a ball valve, a duckbilled valve or the like. The requiredaspects of the flattened tube or valve are that relatively unrestrictedflow is allowed from an attached saline bag to the bloodline but flowfrom the blood line to the branch tube is suppressed progressively asthe negative pressure in the blood line increases. To preferablyaccomplish this, the pulse—suppressing portion of the flexible branchtube is substantially flattened. Accordingly, this tube portion has alumen that can and does reduce its cross-sectional area responsive tonegative pressure in that area to a degree substantially greater thancylindrical tubing. This results in the suppression of negative pressurepulses created by the pumping of blood through the main flow tubing,which negative pressure pulses tend to disrupt the blood-solutioninterface in the branch tube. However, if the tube portion that isflattened is preferably placed in the branch tube between theblood-solution interface and the main blood flow tubing, the effect ofthese negative pressure pulses is damped at the interface area. However,the tube portion, or an alternative valve, can increase itscross-sectional area at any time responsive to positive pressure. Thus,if there is an urgent need to provide saline solution to theextracorporeal blood flow path in the event of a crisis, the tubeportion or valve can expand back to its normal cylindrical shape orseating of the valve is less, so that increased solution flow can passtherethrough.

The flattened branch tube portion may comprise a flattened lumen crosssection that defines a periphery having at least one open groove, whichis transverse to the cross section, to avoid complete closing of thebranch tube under negative pressure. Furthermore, a generallycylindrical, flexible branch tube may be used, the tube being flattenedat the tube portion by a removable slide clamp which comprises a pair ofarms defining a slot between them. The tube portion resides in the slotand, as is preferable, at least one of the arms defines a transverselyextending groove that forms the open groove in the tube portion.

Basically, there is no limit to the types of structures that can be usedin a valve function to provide relatively unrestricted flow from anattached saline bag to the blood line as needed, but also suppressingreverse flow from the blood line to the branch tube that connects to thesaline bag, to suppress fluid pressure pulses particularly at theblood-solution interface, as previously discussed. Particularly, such avalve member closes to restrict flow (but not completely close) whenpressure conditions for reverse flow are present, but it opens wideunder forward flow pressure so that solution may be quickly added to theblood line. Thus, hypotensive patients may receive saline quicklythrough the system if that is needed, but the same system restrictsblood from the blood line from pushing up the branch line by pressureoscillations, which mix the blood and the solution and destroy thediscreet blood-solution interface. However, such a valve member allowsenough reverse flow so that line pressures are equilibrated above theblood-solution interface quickly, so that a hazardous pressure situationis recognized by the pressure transducer.

Typically, such a valve allows full, rapid, 100 percent flow downstreamthrough the branch tube from the solution source to the blood line, butonly allows between about one to fifty percent of that flow in thereverse direction, typically on the order of five to twenty percent ofthe downward flow toward the blood line, under normal pressureconditions.

Further in accordance with this invention, a protector for a female luerconnector is provided, which comprises: an outer sleeve, a centraltransverse wall defined in the outer sleeve, a male luer projectingaxially within the sleeve from the transverse wall to engage the femaleluer connector along with the sleeve. A tube projects axially within thesleeve from the transverse wall into the direction opposed to the maleluer. The tube and the male luer have connected lumens, with the tubehaving an outer end that is substantially recessed within the sleeve.

Accordingly, a female luer connector may be used as a air venting and/ordrain line during priming, for example, with accordance with theteaching of Utterberg U.S. Pat. No. 5,951,870. However, after priming,rather than closing off this line it can be used for the addition ofsupplemental medication, added solution, or the like because the femaleluer connector on the end can have its sterility retained by theprotector of this invention.

Specifically, the protector of this invention has an outer sleeve innerwall which has screw threads or preferably is free of screw threads. Thesleeve inner wall preferably defines axially extending ribs at least onthe side of the transverse wall that carries the male luer, tofacilitate axially sliding connection and retention with the female luerconnector. Furthermore, it is preferred for the tube outer end, whichdoes not need to carry a taper like a male luer, to terminate at a pointno more than about two thirds of the distance from the transverse wallto the end of the outer sleeve which is opposed to the male luer, sothat this tube serves as a spout for the venting of air and primingsolution, and is retained in aseptic condition, since it is recessed inthe outer sleeve and thus protected.

Also, it is preferred for a hinged cap to be attached to the outersleeve in a position which permits closure of the cap over the outersleeve end that is opposed to the male luer , for preservation ofaseptic conditions between priming and subsequent use of the female luerconnector.

Thus, sets for blood processing are provided which exhibit significantdistinction and advantage over the prior art.

DESCRIPTION OF THE DRAWINGS

Referring to the drawings,

FIG. 1 is a plan view of a combined arterial and venous set system inaccordance with this invention, with the respective ends of the arterialand venous sets being connected together to form a closed loop prior touse;

FIG. 2 is a fragmentary, perspective view of the bubble trap chamber ofthe venous set of FIG. 1;

FIG. 3 is a sectional view taken along line 3—3 of the FIG. 2;

FIG. 4 is a perspective view of the underside of the top cap of thechamber of FIG. 2;

FIGS. 5 and 6 are perspective views of a sliding clip utilized in theset arrangement of FIG. 1.

FIG. 7 is an enlarged longitudinal sectional view taken along line 7—7of FIG. 1;

FIG. 7A is an enlarged sectional view taken along line 7A—7A of FIG. 1;

FIG. 8 is an enlarged longitudinal sectional view taken along line 8—8of FIG. 1;

FIG. 9 is an enlarged longitudinal sectional view taken along line 9—9of FIG. 1; and

FIG. 10 is a partial longitudinal sectional view similar to FIG. 9 butrotated 90 degrees about the longitudinal axis.

FIG. 11 is a highly enlarged, longitudinal sectional view of a portionof the set system of FIG. 1, showing an alternative embodiment.

FIGS. 12 and 13 are enlarged portions of FIG. 11, showing the range ofmotion of a valve ball.

FIG. 14 is a sectional view taken along line 14—14 of FIG. 11, with thevalve ball omitted.

FIG. 15 is a longitudinal sectional view similar to FIG. 11, but showingan alternative embodiment in which the pulse suppression device is apartially disabled duckbill valve.

FIG. 16 is a front perspective view of the duckbill valve of FIG. 15.

FIG. 17 is a longitudinal sectional view of an in-line chamber, whichmay be used in a branch line in accordance with this invention, having adifferent design for a pulse suppression member.

FIG. 18 is a perspective view of the pulse suppression member used inthe chamber of FIG. 17.

DESCRIPTION OF SPECIFIC EMBODIMENTS

Referring to the drawings, FIG. 1 shows a combined arterial set and avenous set 10 for hemodialysis comprising arterial set 12 and venous set14, which sets may be used in the conventional manner in conjunctionwith a conventional dialyzer 16 for the performance of hemodialysis.Hemodialyzer 16 may be replaced with a hemoperfusion device or anotherflow through blood treatment device as may be desired.

Arterial set 12 comprises a patient connector 18, which is connected toset tubing 20, closeable by a conventional pressure clamp 22. Set tubing20 communicates with connector 24 for roller pump tubing 44 and having abranch tubing 28 extending out from connector 24.

Branch tubing 28 connects with chamber 29, which connects with tubing 30that communicates with a pressure monitor 37 by connector 36. Chamber 29also connects with a second branching tube 38, which connects with asource of physiological priming solution 40 for priming of the set, andalso for administration to the patient as needed during the dialysisprocedure.

Roller pump tubing 44 may be fitted within a roller pump system 46 forpumping of fluid through the set system. Branch tubing 50 may extendfrom second pump tubing connector 48 for additional connection access tothe system, such as for connection to a heparin source. Connectors 24,48 may be as disclosed in Utterberg U.S. Pat. No. 5,360,395.

Arterial set 12 has an additional length of tubing 52 that extends fromroller pump tubing connector 48 to arterial unit connector 54, which isproportioned to connect to arterial end 56 of dialyzer 16. However, bythis invention, arterial unit connector 54 is integrally connected witha frangible seal 58 to venous unit connector 60, which is adapted toconnect with the venous blood port 62 of dialyzer 16. Preferably, sleeve63 (FIG. 10) surrounds the frangible section to help prevent touchcontamination of the sterile areas during franging (breaking apart).Thus, in an initial condition as shown, unit connectors 54, 60 areinitially connected together, being frangibly breakable along line 58,which then subsequently permits them to be connected to the respectiveports 56, 62 of dialyzer 16 at a desired step in the process of setup ofa dialysis system. Each connector 54, 60 has an integral closure cap 61.

Unit connector 60 of venous set 14 connects with flexible tubing 64, andcommunicates into venous bubble removal chamber 66 through the top capthereof. In normal flow, blood in chamber 66 passes through filter 70and into venous tubing 72, closeable by conventional squeeze clamp 74,to connect to patient venous connector 76. Both patient connectors 18,76 are essentially directly connected together preferably prior tosterilization of the set by the engagement of their respective threadedsealing caps 78, 80 by means of a tubular double connector tube 82,which provides sealing fluid connection between the respective tubularsets and connectors 18,76 while permitting disconnection when desired.For example, patient arterial connector 18 may be disconnected fromdouble connector 82, and then cap 84 may pivot around to close doubleconnector 82 to retain sterility in the venous patient connector 76,while arterial patient connector 18 is being joined to a fistula needle,for example, and connection to the patient's fistula is being effected.

In accordance with this invention, the arterial and venous sets 12, 14are connected together in basically a loop form by the integral joiningof unit connectors 54, 60 along frangible line 58, and by the mutualjoining of arterial and venous patient connectors 18, 76 with doubleconnector tube 82. Preferably, the set may be received in this form insterile condition from the manufacturer to the site where the dialysisis to be performed. The system is mounted in a dialysis machine, withoutconnection to dialyzer 16, in the closed loop condition of FIG. 1.Alternatively, connection may be initially made at this point betweenunit connectors 54, 60 and dialyzer 16, particularly when an internallydry, typically unused dialyzer 16 is provided.

Otherwise, the direct connection between unit connectors 54, 60 may bemaintained during the first steps of priming particularly in thatsituation where dialyzer 16 has a wet interior because it has beenpreviously used, and has been resterilized by conventional processes.Priming solution from container 40 passes through branch tubes 38, 28,filling chamber 29 as well as the rest of the arterial and venous setsystem by pumping of roller pump 46 to cause solution flow in direction86. If desired, simultaneously or sequentially in either order, solutionmay also flow in a reverse direction through tube 20 per arrow 87,typically by gravity solution flow, through the connection betweenpatient connectors 18, 76 and through tubing 72 in direction 87, to fillchamber 66 from the bottom, thus avoiding the trapping of air bubbles infilter 76, with air being vented through branch tubing 88.

By this means, the respective, joined sets 12, 14 can be substantiallyfilled with priming solution, and all undesired air is driven out of theset. Then, if not before, unit connectors 54, 60 may be separated andconnected to the respective ports 56, 62 of dialyzer 16, and furthercirculatory flow may pass through the entire system in direction 86,driven by roller pump 46, for the final recirculation, flushing, and/orrinsing procedure prior to introduction of blood to the system througharterial patient connector 18 and return of blood through connector 76.

A major advantage for performing initial filling and priming of dialysissets 12, 14 in the form of an interconnected loop without dialyzer 16results from the fact that priming can then take place without theinsertion of additional air through the dialyzer. A wet dialyzer willtrap air bubbles in its membrane, resulting in a reduction in dialysisefficiency, so the efficiency is improved by filling the arterial andvenous sets 12, 14 first, and then connecting with particularly a wetdialyzer 16 for the completion of the priming process, which process maybe conventionally performed from then on. Specifically, flow pump 46 maybe a conventional unidirectional pump which pumps in only one flowdirection as needed throughout the entire priming process. Bidirectionalflow from chamber 29 may take place simultaneously in both directions 86and 87 if the flow rate of priming solution through tube 28 is greaterthan the flow rate through pump tubing 44, the excess of the solutionflowing in direction 87 through tube 20 for a rapid, bidirectionalpriming of the respective sets 12, 14.

Referring further to FIGS. 2 through 4, venous bubble removal chamber 66comprises a body 85, typically with a tubular cross section, and top cap89, having a series of apertures for connection with tubing. One of suchconnections comprises main venous flow tubing 64, while another of theconnections comprises branch tubing 88, through which venting of air andpriming solution may take place during the priming process.

Cap 89 may also define an aperture which holds needle pierceableinjection site 90, of conventional design except as otherwise describedherein. Port 91 connects to pressure monitor line 93 (FIG. 1).

In accordance with this invention, flow tubing 64 communicates throughcap 89 into communication with port tube 92 extending into the interiorof chamber 66 and cap 89, having an inner tube end 94 extending belowtop wall 96 of cap 89. Tube end 94 comprises a wall (of the samereference number) that directs flow through the tube circumferentiallyof the bubble trap chamber, through side aperture 98. Thus, bloodinflowing through tube 92 is directed to flow around the innercircumference of chamber 66.

Branch tube 88 communicates with baffle tube 100, which enters thechamber 66 through top wall 96, and terminates at a level which ispreferably closer to top wall 96 than is aperture 98 of inlet tube 92.Thus, baffle tube 100 communicates with the chamber interior, and alsoserves as a baffle along with tube 92 to convert circumferential flow atits level in chamber 66 into turbulent flow, at positions above tube endwall 94 and aperture 98. Thus, inflowing blood provides a rapidlyrotating area of blood at approximately the level of aperture 98.However, at areas nearer to top wall 96, baffle tube 100 and tube 92interfere with the circumferential flow of blood and cause turbulence,which prevents formation of a blood whirlpool having a significant,centrally depressed upper surface. Nevertheless, the rapid,circumferential flow of blood at the level of aperture 98 and slightlybelow in chamber 66 causes microbubbles in the blood to be driven to thecenter of rotation, where the microbubbles can rise upwardly through theturbulent blood area at the level of baffle tube 100, to collect underwall 96 and join in a gas bubble or air space 103 there.

This airspace 103 is spontaneously formed during the priming of this setin chamber 66, which airspace defines a liquid level 101 at about thelower edge of baffle tube 100 at ambient pressure. This is because airis vented out of baffle tube 100 and branch tube 88 during priming.Thus, when sufficient air has been vented so that the blood level risesto reach tube 100, air venting stops. Fluid preferentially passes uptube 100, and the air above the lower end of tube 100 is trapped. Then,during operation under a positive pressure as provided by roller pump46, the airspace 103 will compress, and the liquid level will rise to adegree above the lower end of tube 100. Thus, the desired liquid levelcan be spontaneously formed in chamber 66 on priming.

The air in monitor tube 93, transducer filter 99 and the pressuremonitoring tubing within the dialysis machine 101 have a fixed airvolume.

The position of the tower end of baffle tube 100 and the relatedposition of opening 98 assures that enough air volume at ambientpressure exists in chamber 66 to prevent liquid entering monitor tube 93when the system is fully pressurized at operating flows. Because crosscontamination deaths have occurred when blood from one patient brokethrough a transducer filter and contacted viruses from a previous patentusing the same machine, this invention has great power to save lives.Given the air volume of various machines on the market, the air volumeat ambient above tube end 100 within chamber 66 is preferably at least4cc to attain this safety advantage.

As shown in FIG. 3, top wall 96 of bubble trap chamber 66 defines anaxially depressed portion 104 which, in turn, defines the needlepierceable, resealable injection site 90. Thus, a conventional injectionneedle of at least about ½ inch needle length can be placed throughinjection site 90 to penetrate the injection site and to communicatewith liquid level 101 within chamber 66. As previously described, thispermits continuous contact with the blood supply in chamber 66, so thatEPO, for example, may be administered within pump-flushing, where bloodis drawn into the needle and reintroduced back in to the chamber torinse virtually all EPO from the interior of the needle and syringe,thus assuring essentially a 100 percent administration of the valuabledrug. Air volume in chamber 66 typically of at least 4cc, in combinationwith the invention of depressed portion 104 for the position ofinjection site 90, can provide the combined benefits of sufficientchamber volume for anti-transducer protector wet-out, and use of ½ inchneedles are described above.

Further in accordance with this invention, in FIG. 1 second branchtubing 30 communicates with a conventional pressure monitor 37. Asdescribed in the previously cited patent application Ser. No.09/203,274, it is desirable to connect pressure monitor 37 with asubstantially incompressible liquid pressure transfer path throughsecond branch line 30, chamber 29, and branch line 28 without asignificant amount of compressible gas such as air being present, exceptfor a small amount of air in the tubing next to the transducer protectorso that the transducer protector is not wetted with solution. Also, asmall amount of air is present in the tubing of the transducer deviceitself. As described above, it is highly undesirable for blood to enterpressure monitor 37, which is also connected to dialysis machine 101.Even if a normal protector is used, it is clearly better for the bloodto be spaced from pressure monitor 37. To this end, upon priming, secondbranch line 30 may be filled with priming solution which remains toprovide the substantially more incompressible liquid pressure transferpath, and also to space the blood from pressure monitor 37. Thus, uponoperation of the arterial and venous sets 12 and 14 to transfer blood, ablood-solution interface 106 may be formed typically in branch line 28,so that a continuous liquid pathway is provided to pressure monitor 37,without the blood getting near to the monitor.

However, the pumping action of roller pump 46 against pump tubing 44causes an oscillation in the pressures in the sets, including branchlines 28, 30. Because of the higher density of blood relative to that ofsaline, this oscillation tends to cause the blood-solution interface 106to break up, with blood mixing into the solution. To address this, aslide clamp 108, shown in FIGS. 1, 5 and 6, may be provided tosubstantially flatten a portion of branch tube 28, i.e., that portionwhich occupies the interior of slide clamp 108. Slide clamp 108 ispreferably positioned between blood-solution interface 106 and connector24.

As shown in FIGS. 5 and 6, slide clamp 108 comprises a pair of arms 110,112 defining a slot 114 between them. The flattened tube portion residesin slot 114. Contrary to other slide clamps, slide clamp 108 isproportioned in slot 114 so that flow is not completely blocked throughtube 28, but tube 28 is merely flattened within clamp 108.

It is further preferred for at least one of arms 110, 112, specificallyshown to be arm 110, to define a transversely extending groove 116.Groove 116 forms in the flattened portion of branch tube 28 acorresponding open groove which is generally parallel to thelongitudinal axis of the branch tubing, to avoid complete closing of thebranch tube under negative pressure. Since slide clamp 108 has a slot114 of a width which does not completely close branch tubing 28, itmerely puts the enclosed section of branch tube 28 into a substantiallyflattened configuration, with the result that negative pressure pulsestend to cause the flattened tubing to transiently and spontaneously loselumen area by at least partial collapsing, thus damping the effect ofthe oscillatory pressure and preserving the integrity of preciseblood-solution interface 106, while still permitting transfer ofpressure in set 12 to sensor 37.

However, in the event of an emergency, where the patient needs solutionwith utmost urgency on a life-threatening basis, slide clamp 108 can bequickly removed from branch tube 28, and roller clamp 39 can be openedwide for rapid solution administration. The flattened portion of branchtube 28 can expand out to cylindrical shape again, and thus, it does notprovide a barrier to high volume solution administration. Additionally,second branch tubing 30 can be put into action to provide addedsolution, by disconnecting it from pressure monitor 38 and connecting itto a new source of solution.

As another preferred alternative to the use of slide clamp 108 tostabilize blood-solution interface 106 in the presence of oscillatorypressure in the set 10, pump tubing connector 24 can be modified asconnector 24 a in the manner illustrated in FIGS. 11–14, with slideclamp 108 being not used. Alternatively, another connector or tube ofbranch line 28 below saline/air interface 106 may be modified inequivalent manner as described below.

Connector 24 a connects to pump tubing 44 at one end and to blood flowline 20 at the other end as in the previous embodiment, and injectionsite 25 is provided, being filled with an elastomeric, needle piercingmaterial. Transverse bore 27 communicates between the centralbore 29 ofconnector 24 a, all in a manner similar to the known design of connector24.

Also, connector 24 a provides a parallel connection to branch line 28 asin the previous embodiment.

By way of modification, connector 24 a carries a valve which comprises aball 130, which is trapped in a space 134 that communicates with branchtubing 28 and branching bore 27. Ball valve 130 is capable of movingthrough a range of horizontal positions (from the viewpoint of FIGS.11–13), with the extremes of movement range being shown. In FIG. 12,ball 130 is restrained from further movement to the left by the presenceof cross bar 132, which extends across an end of space 134, which spacecommunicates with transverse bore 27. At the right limit of motion ofball 130, as shown in FIG. 13, ball 130 is stopped from movement by thesmaller, inner diameter of branching tubing 28. However, as shown inboth FIGS. 12 and 13, branch tubing 28 defines a cut-out portion 136.Thus, ball valve 130 has the rare characteristic of being intentionallydisabled from completely sealing against flow between transverse bore 27and tubing 28, although ball valve 130 in its position of FIG. 13constricts and reduces the magnitude of that flow significantly.

Similarly, at the left hand position of FIG. 12, ball 130, restingagainst cross bar 134, still provides an open channel for flow ofsolution from solution source 40 through branch line 28 into transversebore 27 and the main blood flow line comprising tubing sections 20 and44.

The normal flow conditions within connector 24 a are generallysubatmospheric or negative pressure conditions, since connector 24 a isupstream of pump 46. Ball 130 oscillates back and forth as theoscillatory negative pressure conditions created by pump 46 aretransmitted through the liquid to the ball. As ball 130 oscillates intoits right hand extreme position of FIG. 13, driven by pressure peaks ofless negative pressure than the troughs of oscillatory pressure, itsuppresses the transfer of liquid upstream into branch tubing 28, thussuppressing the fluid oscillations and pressure pulses that tend todisrupt blood-solution interface 106. Nevertheless, significant pressurechanges in the system can pass through the barrier provided by ball 130to reach pressure monitor 37, so that alarm conditions can be noted andsignaled despite the flow restriction provided by ball 130, which tendsto stabilize blood-solution interface 106.

If desired, the ball valve incorporating ball 130 could be placed inbranch line 28 or in the bottom of chamber 29. Also, a duckbill-typevalve imparting similar flow characteristics, or other valves, could beused.

Thus, the following effects are achieved:

1. Relatively free flow of saline from tube 30 to arterial line 12 whenI.V. clamp 31 is opened. This is for the reason of quickly alleviatinghypotensive episodes whenever they occur (as well as for rapid primingof the set to save the nurse time). Thus, the valve should be in an openposition whether the driving pressure is only the head pressure of thesaline bag 40 vs a near ambient pressure in the blood line (when bloodpump 46 is off or flowing slowly) or when the driving pressure is highbecause the bloodline pressure is heavily negative due to the sucking ofrapidly flowing bloodpump 46 against the restriction of the arterialfistula needle (not shown).

2. Suppression of blood pressure pulse when I.V. clamp 31 is closed andblood pump 46 is flowing. At low flows the pulse is neither strong orrapid and so the valve doesn't have to seat strongly (i.e. fluid canpass from the arterial line 12 to the I.V. line 28). Because the densityof blood is greater than saline, the saline/blood interface 106 withoutintervention breaks down as the pulse quickens and hammers withincreasing force. Thus, as the bloodpump 46 quickens its rotor speed(quicker pulses) and the blood pressure becomes more negative (higherflows sucking through the fistula needle) the force and the pace of thepressure pulse quickens. Further, at low flows and pressures the“volume” of the pulse is small so fluid passing back through the valvedoes not harm the blood/saline interface or move its position.

At high flows, the valve ball 130 seats somewhat more securely. It stillpasses fluid in order for the correct pressure to be read at transducerfilter 36 (timed delayed because of the pulse suppression), but not somuch as to give the blood pulse enough force and inertia to destroy theblood/saline interface. It should be noted that the pulse is typicallyfrom a higher negative to a lower negative pressure, rather than from anegative to a positive pressure.

The embodiment of FIGS. 15 and 16 how a common duckbill valve 150 can bemodified and used to provide pulse suppression means of the typedescribed above. FIG. 15 is similar in structure to FIG. 11, except forthe type of pulse suppression means shown (the duckbill valve).

Branch line 28 from the set of FIG. 1 connects with connector 24 b,which, like connector 24 a, is positioned to provide double connectionwith pump tubing 44 and blood tubing 20. Injection site 25 b isprovided, being similar to injection site 25 of the previous embodiment.Transverse port 27 b is similar to transverse port 27 of the previousembodiment, as are other components of connector 24 b, except asotherwise described.

Particularly, the moveable ball 134 of the previous embodiment isreplaced by duckbill valve 150, with valve 150 performing the samefunction as the moveable ball in the previous embodiment.

Referring to FIG. 16, a perspective view of duckbill valve 150 is shown.Valve 150 may be a common, commercially available rubber duckbill valvewhich operates as a one way valve in an entirely known manner. However,in accordance with this invention, one or more holes 152 are punchedinto valve 150, so that the permitted flow in the direction fromconnector 24 b and through branch tubing 28 is restricted but notcompletely blocked, so that constant pressure communication between theblood line and branch tubing 28 is achieved moment-by-moment. At thesame time, high volume flow through branch line 28 to connector 24 b andfrom there to the blood flow circuit remains possible. Typically, thefluid backflow through duckbill valve 150 into branch line 28 can beabout five percent of the forward liquid flow from branch line 28 intothe blood flow circuit at pressures normally used, so that pressurepulses do not disrupt blood-solution interface 106.

FIGS. 17 and 18 show another embodiment of pulse suppression means inaccordance with this invention.

FIG. 17 shows in line chamber 29 a, serving as a substitute for chamber29 in FIG. 1. The pulse suppression member 160 occupies chamber 29 a,thus being positioned at the end 171 of branch line 28, which is opposedto the end of the branch line which connects with connectors 24, 24 a,and 24 b in the various embodiments. This shows the wide variability ofthe location of the pulse suppressing member for protectionblood-solution interface 106. Chamber 29 a connects at its bottom withbranch tubing 28, and, like the embodiments of FIGS. 11–15, no slidingclamp like clamp 108 is required. At the top, chamber 29 a may connectwith tubing 30 which, in turn, connects with a pressure monitor 37.Chamber 29 a also connects with tubing 38, which connects with thesource of solution 40.

Chamber 29 a carries a movable arrowhead member 160 as the pulsesuppression means, which reciprocates for a short distance upwardly anddownwardly in chamber 29 a, being wider than and thus retained byconstricted neck 162 of chamber 29 a, through which constricted portion163 of arrowhead member 160 extends. Head 164 of arrowhead member 160 ispositioned above constricted neck 162 and, as shown in FIG. 18, isflattened on its respective sides as shown to provide a second dimensionof width that is no more than half the wider dimension of width. Thus,when positive pressure is present in chamber 29 a, there is still goodroom for flow of fluid out the bottom of chamber 29 a, past the flatfaces 166 of head 164 into tube 28. However, when a pressure pulse inbranch line 28 is projected upwardly to arrowhead number 160, the pulsestrikes flanged bottom 168 of arrowhead member 160, driving arrowheadmember 160 upwardly so that flange 170 engages annular, constricted neck162 of chamber 29 a. However, this does not absolutely halt upward flowfrom tube 28 into chamber 29 a, by the design of the system. Typically,one would engineer a valve-like structure of this type to seal well.However, in this instance, the system will be designed to seal onlypartially, providing a leaking upward flow that is at least one percentof the downward flow through the same system from chamber 29 a. This canbe accomplished in a variety of ways; by one or more longitudinalgrooves or apertures in flange 170, by simply roughening the surface offlange 170 to allow a small amount of upward flow in all conditions, byadjustment of the draft angle in the vicinity of flange 170, or by acombination of these techniques.

Thus, as an oscillatory pressure from the blood line is provided throughbranch tube 28, arrowhead member 160 oscillates upwardly and downwardly,suppressing but not eliminating the flow and pressure communicationbetween branch line 28 and chamber 29 a. Thus, the pressure conditionsare damped in branch line 28, having the effect of tending to preservethe integrity of blood-solution interface 106.

Inlet flow distribution member 172 has a closed bottom end, but allowsthe flow of solution to enter chamber 29 a sideways through a pluralityof apertures 176, so that the solution tends to impinge the wall ofchamber 29 a upon rapid infusion.

Another example of the pressure pulse suppression means may simply beprovided by the use of a relatively enlarged diameter of branch tubing28. For example, when a maximum flow through blood flow line 20, 44, 52is about 500 ml. per minute and a two roller pump 46 is used pressure,pulses may be significantly suppressed by the use of a branch tube 28having an inner diameter of at least 4.5 millimeters and preferably 5–8mm. In a specific embodiment of this, pump segment tubing 44 may have aninner diameter of eight millimeters and an outer diameter of 12millimeters. Thus, blood-solution interface 106 is not seriouslydisturbed by pressure oscillations, which oscillations are damped by thelarger diameter tubing 28.

Further in accordance with this invention, venting line 88 may carry aconnector 110 such as a female luer (FIGS. 1 and 7), which, by thisinvention, may be subsequently used for other purposes by retention ofits aseptic condition while being used for venting. For example, it alsocan be connected to a solution or blood container in the event of anemergency.

A protector 112 is provided for connector 110, which protector comprisesan outer sleeve 114, and a central, transverse wall 115 defined in outersleeve 114. A male luer 116 projects axially within sleeve 114 fromtransverse wall 115 to engage the female luer connector 110 along withsleeve 114, so that the female luer connector 110 is enclosed within andwithout. A tube 118 projects axially within sleeve 112 from thetransverse wall in the direction opposed to male luer 116, the tube andmale luer having connected lumens 120. Tube 118 has an outer end that issubstantially recessed within the sleeve 114. Thus, aseptic conditionscan be retained as air and priming solution pass through tube 88 duringpriming and out of female luer 110, due to the protective action of theprotector of this invention.

It should be noted that sleeve 114 may have an inner wall which is freeof screw threads, but rather defines axially extending ribs 122 tofacilitate axially sliding connection and retention with luer connector110. Also, a hinged cap 124 may be attached to outer sleeve 114 in aposition which permits closure of the cap over the outer sleeve end 126that is opposed to the male luer 116, to surround and seal it.

By this means, the female luer connector 110, even though wet, can beaseptically protected so that it can be reused in another functionduring the blood treatment process if needed.

The above has been offered for illustrative purposes only, and is notintended to limit the scope of the invention of this application, whichis as defined in the claims below.

1. A tubular medical set for the transfer of blood, said set having mainblood flow tubing and a flexible branch tube connected in branchingrelation to the main tubing for connection to a source of physiological,cell-free solution and for retaining a blood-solution interface, saidset further comprising a device to suppress pressure pulses tending todisrupt said blood-solution interface in said branch tube while allowingthe transfer of pressure across said pressure pulse suppression means atessentially all times and permitting at any time the relativelyunrestricted flow of said cell free solution through said branch tubingto the main blood flow tubing, said device to suppress pressure pulsescomprising a moveable member that freely, by action of flowing fluid,moves through a range of positions, said device to suppress pressurepulses being designed to permit fluid flow in the direction opposed tosaid relatively unrestricted flow of said cell free solution in anamount 1 to 50 percent of the magnitude of said relatively unrestrictedflow at maximum rate, under conditions of normal use.
 2. The tubularmedical set of claim 1 in which said moveable member comprises a ball.3. The tubular medical set of claim 1 in which said device to suppresspressure pulses comprises a duckbill valve having an imperfection,causing the valve to permit large volume flow in one direction from thebranch tube to the main blood flow tubing and a smaller volume of flowin the opposite direction.
 4. The tubular medical set of claim 1 inwhich said pressure pulse suppression means comprises a moveable memberhaving a central, reduced-width portion bracketed by enlarged-widthportions for partial sealing, said moveable member being positioned inan in-line flow chamber in the flexible branch tube, said flow chamberdefining an inwardly extending constriction which extends to retain saidcentral, reduced-width portion of the moveable member, to permit saidmoveable member to reciprocate back and forth relative to saidconstriction so that one enlarged width portion or another enlargedwidth portion engages said constricted portion of the chamber so thatbidirectional flow is permitted, the enlarged width portions beingshaped whereby flow of liquid through said constricted portion in onedirection is greater in magnitude than the liquid flow in the otherdirection under conditions of use, said one direction being from thebranch tube to the main blood flow tubing.
 5. The tubular medical set ofclaim 4 in which the increased-width portion pointing away from the mainblood flow tubing defines a second dimension of width that is no morethan about half a first dimension of width, to facilitate liquid flow.6. A tubular medical fluid set comprising an in-line bubble trap chamberhaving a top wall and a tubular side wall, said top wall defining a portwhich communicates with flow tubing of said tubular set, said portcommunicating with a port tube extending longitudinally into saidchamber adjacent to said side wall, said port tube having an inner tubeend spaced below said top wall, said inner tube end directing flow outof said tube circumferentially of said bubble trap chamber, wherebymedical fluid entering said chamber through said port is directedcircumferentially about said chamber side wall, said chamber having acomponent which defines a baffle to convert circumferential flow abovesaid tube end into turbulent flow, to prevent formation of a whirlpoolhaving a significant, centrally depressed upper surface.
 7. The tubularset of claim 6 in which said chamber defines a liquid level thereinhaving a predetermined air volume which has a volume of at least 4 cc.8. The tubular set of claim 6 in which said medical fluid in saidchamber below said inner tube end is free to flow circumferentiallywithout direct interference by a baffle.
 9. The tubular set of claim 6in which said baffle comprises a tube other than said port tube, saidother tube being joined to an inner surface of a side wall of saidbubble trap.
 10. The tubular set of claim 6 in which said inner tube enddefines a single flow inlet.
 11. A tubular medical fluid set comprisingan in-line bubble trap chamber having a top wall, a port communicatingwith flow tubing of the tubular set, said port communicating with a porttube extending into said chamber, said port tube having an inner tubeend spaced below said top wall, said tube end being positioned to directflow out of said tube circumferentially into the bubble trap chamber,whereby blood entering said chamber through said inner tube end isdirected circumferentially about said chamber, said chamber having acomponent other than said port tube which serves as a baffle, saidbaffle being radially outwardly spaced from the center of said chamberand extending longitudinally along an upper portion of said chamber andterminating at a position above said port tube, to convertcircumferential flow into turbulent flow at the level of said baffle,and to prevent formation of a blood whirlpool having a significant,centrally depressed upper surface, and whereby blood at about the levelof the tube end and below is free to circumferentially flow withoutinterference by the baffle.
 12. The tubular set of claim 11 in whichsaid baffle comprises a tube that is joined to an inner surface of aside wall of said bubble trap.
 13. The tubular set of claim 12 in whichsaid port tube also extends longitudinally and comprises a tube that isjoined to an inner surface of a side wall of said bubble trap.
 14. Thetubular set of claim 11 in which said chamber defines a liquid leveltherein having a predetermined air volume which has a volume of at least4 cc.
 15. The tubular set of claim 11 in which said port tube alsoextends longitudinally and comprises a tube that is joined to an innersurface of a side wall of said bubble trap.
 16. The tubular set of claim11 in which said inner tube end defines a single flow inlet.
 17. Atubular medical fluid set comprising an in-line bubble trap chamberhaving a top wall, a port communicating with flow tubing of the tubularset, said port communicating with a port tube extending longitudinallyinto said chamber within a side wall of said chamber while being spacedfrom the longitudinal axis of said bubble trap chamber, said port tubehaving an inner tube end spaced below said top wall, said inner tube endbeing positioned to direct flow out of said tube whereby blood enteringsaid chamber through said inner tube end is directed circumferentiallyabout said chamber, to provide circumferential flow of blood below saidinner tube end, while blood in said chamber above said tube end issuppressed from substantial circumferential flow by the longitudinallyextending port tube in said chamber, so that circumferential flow isconverted into turbulent flow above said tube end.
 18. The tubular setof claim 17 in which said medical fluid in said chamber below said innertube end is free to flow circumferentially without direct interferenceby a baffle.
 19. The tubular set of claim 17 in which said inner tubeend defines a single flow inlet.